openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/crypto/krb5/Kconfig b/crypto/krb5/Kconfig
new file mode 100644
index 000000000..4d0476e13
--- /dev/null
+++ b/crypto/krb5/Kconfig
@@ -0,0 +1,26 @@
+config CRYPTO_KRB5
+	tristate "Kerberos 5 crypto"
+	select CRYPTO_MANAGER
+	select CRYPTO_KRB5ENC
+	select CRYPTO_AUTHENC
+	select CRYPTO_SKCIPHER
+	select CRYPTO_HASH_INFO
+	select CRYPTO_HMAC
+	select CRYPTO_CMAC
+	select CRYPTO_SHA1
+	select CRYPTO_SHA256
+	select CRYPTO_SHA512
+	select CRYPTO_CBC
+	select CRYPTO_CTS
+	select CRYPTO_AES
+	select CRYPTO_CAMELLIA
+	help
+	  Provide a library for provision of Kerberos-5-based crypto.  This is
+	  intended for network filesystems to use.
+
+config CRYPTO_KRB5_SELFTESTS
+	bool "Kerberos 5 crypto selftests"
+	depends on CRYPTO_KRB5
+	help
+	  Turn on some self-testing for the kerberos 5 crypto functions.  These
+	  will be performed on module load or boot, if compiled in.